Grinding machines, especially the class of machines such as the STEP-MASTER manufactured by Warner & Swasey of Cleveland, Ohio were designed with the plane of the grinding wheel mounted at an oblique angle with respect to the workpiece. This type of machine can be used to grind as an example, the inside of a shoulder or a fillet radius. This type of arrangement is shown in FIG. 1 which illustrates the workpiece generally designated as 16 having a shoulder or fillet radius 12. The grinding wheel 18 mounted at an oblique angle .phi.. The grinding wheel 18 may be dressed or shaped to the desired shape of the interior dimension of the shoulder. An advantage of this design is that the workpiece 16 and wheel 18 can be moved into contacting engagement by motion about a single axis that is movement parallel to the plane of the grinding wheel.
The inclusion of computer numerical controls to these machines has heretofore done little to alleviate the limitation of these machines caused by the oblique mounting of the grinding implements such as the wheel 14 relative to the workpiece. Known techniques of circular interpolation for cutting circles and other continuous curves are not directly applicable to this type of machine because of the oblique mounting of the grinding implement.
An object of the present invention is to provide a numerical control system for a grinding machine of the type having an obliquely mounted grinding implement. A further object of the present invention is to provide this numerical control system with a capability of controlling the obliquely mounted grinding implement or for controlling the relative relationship of the workpiece and the grinding implement such that contouring can be readily performed by the obliquely mounted grinding implement.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.